Hydrofoils allow lifting the board out of the water during kite surfing or jet skiing, thereby reducing the flow resistance. They generally comprise a keel fin, hereinafter also referred to as hydrofoil fin, having a first end portion for attachment to the board and a front wing and rear wing, which are arranged one behind the other in the direction of travel and connected to a second end portion of the keel fin. If the board raises from the water only a portion of hydrofoil fin and the two wings remain immersed in the water. In this situation, large bending and torsional moments may occur at the hydrofoil fin.
The object of the invention is to provide a hydrofoil fin which has a low weight and at the same time high flexural and torsional stiffness.